Self-centering chuck.



B; BOMBORN & A. HOFFMANN;

SELF (ENTERING (:HUGKJ. APPLICATION FILED MAR. 1 1909.

Patentewec. "i, 1909.

Magma,

Witnassw.

B, BOMBORN & A. HQPF N.

. SELF a 1 (6mm ,rrorrmnnn Assist,

snnr-cn g'rnarno annex.

To all g V 1 Be it kn'm'vn 'tliatwe'fTBriRNHAno BOMBORN, I engineer,citizen of the Kingdom of Prussia,

residing at Berlin, ififthe Empire of Ger-v. many, and ALEXANDEQHonrMANN, engineer, citizen of the Empire of Russia, residing at Berlin,in the Empire of Germany, have invented certain new and usefulImprovements 1n Self- (Jeirter i ng hucks,of which the following is'aispecifi' can: We v This "inventi'o relate automatically ter ng hu k bf." h me r i machinesoflatlies ahd lial'siforits object to provide asimple, cheap and eflicient device,

which may be connected with or formed in the face plate or surface plateof such machines, for automatically centering the drills.

The invention consists in providing the chuck with a central re'cesstoreceive. the shank of the drill, andfabore extending through thechuck-head .arranged transversely to. the axis of the recess, saidborecontaining a gripping-device which mmprises a core mova lelongitudinally of the bore and having a transverse aperture whose wallor walls are parallel to the'axis of said recess against which wall thedrill is clamped by means of a screw or screws working in the corfimeansbeing provided to prevent displacement of the core in any directionotherthan longitudinal displacement.

In the accompanying drawings we have shown in detail certainadvantageous forms of embodiment of the invention and .in

which k Figure 1 is a longitudinal section of one form of clutch. Fig. 2is a detail plan view of the gripping device. Fig. 3 is an end view ofthe latter. Figs. 4 and 5 are views like Figs. 2 and 3 respectively of amodi- 'fied form of gripping device. Fig. 6 is an,

elevation of a modified form of chuck. Figs. 7 and 8 are cross sectionson line AB,of Fig. 9 and showing the core in difl'erent po it sitionsdue to the diflerence in the size of the drills. Fig. 9 is a sectionalview of a chuck attached to a lathe head shown in elevation. Fig. 10 isan elevation ofthe clutch provided with a modified form of stock. Fig.11 is an elevation part1 in section of further modified forms of c uck.-Fig. 12

I Speciflcatino Letters Patent.

formed in one end ofthe core.

is a similar view of the left side of Fig. 11

eferring to Fig. 1, the numeral 4 desig- HQFFMANN, or BniiLInoEaMAnY;snow Jell SAID BOM' ORN. I I

L raeent a nee. a, woo. pliation filed Halfch-16 1909. man ac-483,762.;f

. zia' ndFig. 13 is a samaltn line C-D nates the stock of the chuckhaving a centred conical recess 5 and an integral head portion 9 whichlattemhas a cylindrical bore 16 which extends thigough the head andwhose longitudinal axis is perpendicular tof the axis of the recess 5.In the bore 1 is mounted a core 2 adapted to move longitudinally thereinbut held againstrotationby means of pins? fixed in the head andprojecting into corresponding holes 17 Fig. 3', The pins may bedispensed with and rotation of the core in the bore may be prevented byforming the core as 2, and bore rectangular in cross section as, shownin Figs. 4 and 5. The core 2 is further provided with a transverse slot8 preferably of the form shown in Figs.

2 and 4 which. registers withthe recess yf and with an aperture in thechuck-head diametricallyopposite said recess. The Wall 18 of said slot 8is parallelto the axis of the recess 5, and a screw or screws 3, one ofwhich is shown, works in the core to and from said wall andperpendicular thereto. When a drill-or similar tool as 6 is insertedinto the chuck the end of the shank of Instead of formlng the stock andchuck in the tool engages the centering wallsof the one piece, as abovedescribed, they may be made separate, the stock 12, Figs. 6', H and 12and stock 14, Fig. 10 which is made square, being provided with screwthreads v13 which screw into a threaded socket formed inthe head '9. Theformation of the stock and head in separate parts has the advantage ofeasy production and makes it possible to supply a head capable offitting the stock of any machine. The stocks and heads are usually madeof wrought iron while the core is made of steel, but any suitablematerial may be used'for either. The preferred, and it is believed themost advantageous,

screwed to a coupling member 15 designed to be screwed to a lathespindle, not shown.

- nal slot 10 into with the arrangement of the pinsshown in ways,

' venting .into which pro ects an extension 17' formed :0

form of connection is by a screw such as 13, l but other connectionscould be adopted, provery essential feature, is more easily accomvided agood centering is attained, for explished than in known existingconstrucample the parts could be connected by small tions. screws. Weclaim In Fig. .9 An automatically centering chuck comprising a stockhaving a tool centering apcn head detachably connected and a perfectfitting of the parts, which is a the chuck head 9 is shown ture therein,a

with the stock having a cylindrical bore extendingtherethroughperpendicular to the axis ot the tool centering aperture, acylindrical core mounted in the bore of substantially ,the samedimensions of the latter and provided with-a tool receiving slot passingAnother. convenient arrangement for preventing rotation of the core inthe bore is illustrated in Figs. (5 to 10, wherein the core is providedwith a straight lateral longitudiwhich projects the end 'offa screw orpin 11 mounted in the chuckhead. The length of the slot 10 is preferablysuch that the longitudinal movement of the core is limited so that thelatter cannot drop out at the ends of the bore 16 which is possible cessformed in a portion of its periphery, said recess adapted to receive anextension formed on the stock, said extension serving to preventrotation of the core by engaging Fig. 1. v the-bottom of the recess andto'limit the The invention may be carried out in many I longitudinalmovement of the core in the other than those above described as foregrample, the head 9 may be sufllciently large to-permit of theformation of the centering recess 5"therein. The means for prewalls ofthe recess, and a screw in the core wholly within the bore to clamp atool against the walls of the transverse slot.

the rotation of the core in the bore In testimony .whereof we afiix oursignashown in 'Figs. 11 to 13, consists in forming tures in presence oftwo witnesses.

in the, periphery of the core a fiat recess 18 I BERNHARD BOMBORNALEXANDER HOFFMANN.

Vitnesses WOLDEMAR HAUPT, HENRY HASPER.

on the stock. a

By making the bore cylindrical and extending it entirely through thehead the method of manufacture is greatly simplified bore by forming anabutment for the end transversely through it and with afiat re-

